Two weeks after releasing the first beta of OS X 10.10.5, Apple today has released beta 2 of the operating system to developers. The second beta build carries the build number 14F19a and is available to testers via the Mac App Store now.
Earlier today, Apple released beta 2 of iOS 8.4.1 to developers to test. Seeing that OS X El Capitan is slated to be released this fall, it seems likely that 10.10.5 is the last update Yosemite will see. Developers currently, of course, are focused on developing for El Capitan and iOS 9, which means these more incremental updates are likely not seeing as much usage. It remains unclear, however, when iOS 8.4.1 and OS X 10.10.5 will rollout to the public.
OS X 10.10.5 beta 2 is available via the Mac App Store now and should be available via the Developer Center soon, with a full changelog, as well.